The tuning chronicles: emulsion/driveability
06-02-2015, 06:46 AM
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The tuning chronicles: emulsion/driveability I will start by saying that I couldn't have done it without this site (speedtigger in particular) and the guys over on Yellow bullet. This may be repetitive but I want to share my experience and get the info out there for more to see/know. I apologize for the long read, but im baffled by this.
These two threads are invaluable, if you have the time. Read every last bit of them.
https://ls1tech.com/forums/carburete...cd-tuners.html
http://www.yellowbullet.com/forum/sh...d.php?t=490296
There is another 28 page thread on the bullet that is even better, I cant seem to find it right now.
Since I have had the car on the road the last two years I have been non stop playing with the carb to get it better. It always ran good, but I was never happy with it. In fact, my quick fuel carb was starting to put a bad taste in my mouth because I have never had such a hard time nailing down part throttle AFR's. The idle would always fluctuate and it had THE STRANGEST lean spots in the fuel curve. I tried everything, playing with IFR's, PVCR's and emulsion jets...nothing worked. I about had it and was close to buying a new carb, thinking this one just flat out cant meter well on my engine.
I, along with many other carb LS guys I had huge squirters, aggressive pump cams and 50cc pumps. I had no hesitations, it revved smooth but always seemed just a tad bit lazy to me.
My first step to REAL success was digging through my pile of old holley carb parts, I found two primary metering blocks off a couple of 650's. I started by swapping out just the primary block. Started it up and retuned the idle. I could already tell things were better. I took it down the road and it was pig ******* rich...what the heck, this was a bad idea I thought. I disconnected the secondary linkage and went back out...still rich at WOT so I re-jetted all the way down to 66's from my previous 74's in the primaries. This yielded a Perfect 13.0- 13.5AFR at WOT with the secondary's disconnected. There was still a slightly lean spot close to idle so I dropped the IAB's to a 61 from 65 and it cured that and further smoothed out my idle AFR's. It still ran rich at moderate acceleration, around 40mph. I put a vacuum gauge on the car and took it back out, my 10.5 power valve was now opening WAY sooner than it ever had and causing a rich condition. Not having a 8.5" which the gauge showed it would like I put a 6.5 in just to see the effect and it brought things to about 15-16:1 and would just ever so slightly misfire if I leaned on it just a little more before the PV opened.
Now the secondary's: Not as much to tell here.
I swapped the secondary block. Now my idle AFR's are rock steady, only fluctuating a few points up and down, the car has never been this smooth. I revved it up and it stumbled HARD and showed lean on my wideband once the secondary's open. It was hesitating so bad that it would stall when I let off the throttle...it was now a rich condition misfire. I could tell because when I restarted the car it idled rich and eventually cleared up after a few seconds of running. I put a 35 squirter in the back and the hesitation went away, I put a 31 in and it absolutely screams once they secondary's open. I can still see a rich surge on the wideband from the pumps so I may even try a 28, but I don't think it will like it in cold weather.
Conclusion:
I think my quickfuel metering blocks are junk, I may throw then in the woods. The fuel curve is smooth as can be, the transitions are perfect and it completely changed how my motor ran. It runs harder, cleaner, leaner and crisper than it ever has. I still have my 50cc accelerator pump in the back because I didn't feel like swapping it, but I may just leave it for now. The car now idles around 14:1 part throttle accelerates around 13.5 and cruises in the 14's. Wide open throttle is right where I need it to be with MUCh small jets and it revs so clean now with the smaller squirters. I couldn't be happier.
My current setup
Quick fuel HR 650
36 HSAB
61 LSAB
65 Primary jet
79 Secondary jet
8.5 PV
blue primary cam with a 31 squirter
brown 50cc secondary cam with a 31 squirter
the emulsion package in these blocks has the IFR in the lower position, 2 ports and a tiny kill bleed. I don't even know what size they are as I didn't take the time measure. Same with the PVCR, but im guessing they are quite large based on my jet spread.
These results are exactly what the two threads I posted earlier are trying to achieve and I just couldn't do it with my QuickFuel Blocks, why? Im not sure.
These two threads are invaluable, if you have the time. Read every last bit of them.
https://ls1tech.com/forums/carburete...cd-tuners.html
http://www.yellowbullet.com/forum/sh...d.php?t=490296
There is another 28 page thread on the bullet that is even better, I cant seem to find it right now.
Since I have had the car on the road the last two years I have been non stop playing with the carb to get it better. It always ran good, but I was never happy with it. In fact, my quick fuel carb was starting to put a bad taste in my mouth because I have never had such a hard time nailing down part throttle AFR's. The idle would always fluctuate and it had THE STRANGEST lean spots in the fuel curve. I tried everything, playing with IFR's, PVCR's and emulsion jets...nothing worked. I about had it and was close to buying a new carb, thinking this one just flat out cant meter well on my engine.
I, along with many other carb LS guys I had huge squirters, aggressive pump cams and 50cc pumps. I had no hesitations, it revved smooth but always seemed just a tad bit lazy to me.
My first step to REAL success was digging through my pile of old holley carb parts, I found two primary metering blocks off a couple of 650's. I started by swapping out just the primary block. Started it up and retuned the idle. I could already tell things were better. I took it down the road and it was pig ******* rich...what the heck, this was a bad idea I thought. I disconnected the secondary linkage and went back out...still rich at WOT so I re-jetted all the way down to 66's from my previous 74's in the primaries. This yielded a Perfect 13.0- 13.5AFR at WOT with the secondary's disconnected. There was still a slightly lean spot close to idle so I dropped the IAB's to a 61 from 65 and it cured that and further smoothed out my idle AFR's. It still ran rich at moderate acceleration, around 40mph. I put a vacuum gauge on the car and took it back out, my 10.5 power valve was now opening WAY sooner than it ever had and causing a rich condition. Not having a 8.5" which the gauge showed it would like I put a 6.5 in just to see the effect and it brought things to about 15-16:1 and would just ever so slightly misfire if I leaned on it just a little more before the PV opened.
Now the secondary's: Not as much to tell here.
I swapped the secondary block. Now my idle AFR's are rock steady, only fluctuating a few points up and down, the car has never been this smooth. I revved it up and it stumbled HARD and showed lean on my wideband once the secondary's open. It was hesitating so bad that it would stall when I let off the throttle...it was now a rich condition misfire. I could tell because when I restarted the car it idled rich and eventually cleared up after a few seconds of running. I put a 35 squirter in the back and the hesitation went away, I put a 31 in and it absolutely screams once they secondary's open. I can still see a rich surge on the wideband from the pumps so I may even try a 28, but I don't think it will like it in cold weather.
Conclusion:
I think my quickfuel metering blocks are junk, I may throw then in the woods. The fuel curve is smooth as can be, the transitions are perfect and it completely changed how my motor ran. It runs harder, cleaner, leaner and crisper than it ever has. I still have my 50cc accelerator pump in the back because I didn't feel like swapping it, but I may just leave it for now. The car now idles around 14:1 part throttle accelerates around 13.5 and cruises in the 14's. Wide open throttle is right where I need it to be with MUCh small jets and it revs so clean now with the smaller squirters. I couldn't be happier.
My current setup
Quick fuel HR 650
36 HSAB
61 LSAB
65 Primary jet
79 Secondary jet
8.5 PV
blue primary cam with a 31 squirter
brown 50cc secondary cam with a 31 squirter
the emulsion package in these blocks has the IFR in the lower position, 2 ports and a tiny kill bleed. I don't even know what size they are as I didn't take the time measure. Same with the PVCR, but im guessing they are quite large based on my jet spread.
These results are exactly what the two threads I posted earlier are trying to achieve and I just couldn't do it with my QuickFuel Blocks, why? Im not sure.
06-02-2015, 02:03 PM
#2
Good to hear. Glad you got it dialed in.
Guess those old Holley guys may have known something after all.
So basically the story here is trust Holley and don't F with the emulsion circuits?
Oh, and 50 cc pumps means you are doing it wrong.
Guess those old Holley guys may have known something after all.
So basically the story here is trust Holley and don't F with the emulsion circuits?
Oh, and 50 cc pumps means you are doing it wrong.
06-02-2015, 02:19 PM
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Basically that's it. The old holley blocks worked well, I won't make a blanket statement saying you should never mess with them but in my situation they work very well. And as far as the pumps go, I agree. However, the motor absolutely needed them to fill the gap left by a choppy idle circuit and erratic fuel curve. The new (old) blocks have a much smoother and consistent fuel flow that leave no areas of the fuel curve that need artificial smoothing from large pump shots. The old blocks weren't necessarily lean, just provided very poor fuel mixture quality I think.
Last edited by Horsepwraddict; 06-02-2015 at 02:32 PM.
06-02-2015, 02:35 PM
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I had some time today and I put the 30cc pump back in the secondary's. It likes it just fine with 30cc pumps, 31 squirters front and rear and blue cams front and back
